Lead-zinc tailing-based geopolymer thermal insulation material and preparation method thereof

Abstract

The application discloses a lead-zinc tailing-based geopolymer thermal insulation material and a preparation method thereof, and relates to the technical field of engineering materials, which comprises the following components in parts by weight: 50 parts of lead-zinc tailing, 50 parts of fly ash, 4-16 parts of phenolic resin, 0-1 part of glass fiber, 0.8-1 part of hydrogen peroxide solid powder, and 60-128 parts of alkali activator. The application obtains a thermal insulation material with low thermal conductivity, high dimensional stability and environmental durability. The application combines lead-zinc tailing and fly ash as main raw materials, an optimized modulus alkali activator, precisely controlled liquid-solid ratio and silicon-aluminum ratio, and staged gradient stirring and stepwise solidification-curing-hydrothermal process, so that the whole scheme realizes the synergistic effect of solid waste resource utilization, accurate control of pore structure and material function integration, and is especially suitable for building energy saving, industrial thermal insulation and other scenes with high requirements for lightweight, fireproof and environmentally-friendly thermal insulation materials.

Description

Technical Field

[0001] This invention relates to the field of engineering materials technology, and in particular to a lead-zinc tailings base geopolymer thermal insulation material and its preparation method. Background Technology

[0002] Geopolymers, as an environmentally friendly building material, have attracted much attention in the field of thermal insulation. Utilizing solid wastes such as fly ash and lead-zinc tailings to prepare geopolymers is an effective way to achieve solid waste resource utilization. Current technologies typically mix the two materials, solidify them under alkali activation to form a geopolymer framework, and then add physical foaming agents to create pores to achieve lightweight insulation. While this method achieves lightweight properties, it is difficult to systematically optimize the material's performance.

[0003] Traditional foaming produces random and unstable pore structures. The pore walls are composed of geopolymer gels with limited strength, which are prone to collapse under stress, resulting in reduced thermal insulation performance and insufficient mechanical strength. Existing technologies lack a systematic method that can actively regulate the pore wall structure and interface while introducing high porosity, thereby synergistically improving thermal insulation, strength and stability, which restricts the development of high-performance solid waste-based thermal insulation materials. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a lead-zinc tailings base geopolymer thermal insulation material to solve the technical problem that the unstable pore structure and low pore wall strength of traditional geopolymer foam materials make it difficult to synergistically improve their thermal insulation and mechanical properties.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a lead-zinc tailings-based geopolymer thermal insulation material, comprising, by weight, the following components: 50 parts lead-zinc tailings, 50 parts fly ash, 4-16 parts phenolic resin, 0-1 parts glass fiber, 0.8-1 parts hydrogen peroxide solid powder, and 60-128 parts alkali activator.

[0007] Furthermore, this material is composed of lead-zinc tailings, fly ash, phenolic resin, glass fiber, hydrogen peroxide solid powder, and an alkali activator in a specific ratio. Lead-zinc tailings and fly ash, as the main silica-alumina precursors, are the basic raw materials for the geopolymerization reaction. The addition of phenolic resin plays a crucial role in foaming, pore formation, and interface strengthening in subsequent processes. Glass fiber serves as a reinforcing phase to improve the material's toughness. Hydrogen peroxide solid powder acts as an auxiliary foaming agent, synergistically generating initial pores with the phenolic resin. The alkali activator is a key component driving the geopolymerization reaction; its dosage and composition directly determine the formation efficiency and structural stability of the gel network. The synergistic effect of each component aims to achieve precise construction of the pore structure and comprehensive optimization of material properties.

[0008] As a preferred embodiment of the lead-zinc tailings base geopolymer thermal insulation material of the present invention, the alkaline activator is composed of sodium hydroxide, sodium silicate and water, and its modulus is 2-2.6.

[0009] Furthermore, the alkali activator is prepared by combining sodium hydroxide, sodium silicate, and water. Its modulus (the molar ratio of SiO2 / Na2O) is a key parameter for regulating the rate of geopolymerization, product structure, and final properties. This scheme precisely controls it within the range of 2-2.6. At this modulus, the alkali activator can provide a suitable alkaline environment and active silica species, effectively activating the activity of fly ash and lead-zinc tailings, promoting the rapid and stable formation of a three-dimensional aluminosilicate gel network, while avoiding excessively rapid reactions and loose structures due to excessive alkalinity, or affecting the integrity and strength of the gel structure due to insufficient sodium silicate supply.

[0010] As a preferred embodiment of the lead-zinc tailings base geopolymer thermal insulation material of the present invention, the liquid-to-solid mass ratio of the material is 0.4-0.55, and the silicon-to-aluminum molar ratio is 2.2-2.8.

[0011] Furthermore, to obtain ideal process performance and final product structure, this scheme precisely controls the slurry state and chemical composition. The liquid-to-solid mass ratio is limited to 0.4-0.55. This ratio ensures that the slurry has suitable fluidity and castability, while avoiding excessive water leading to excessive porosity and decreased strength after curing, or insufficient water causing uneven mixing and incomplete reaction. The silica-alumina molar ratio is set at 2.2-2.8. This range aims to optimize the chemical composition of the geopolymer gel, enabling it to generate more three-dimensional network structures with good mechanical properties and stability.

[0012] As a preferred embodiment of the lead-zinc tailings base geopolymer thermal insulation material of the present invention, wherein: the phenolic resin is a thermoplastic phenolic resin, and the glass fiber is an alkali-free glass fiber with a length of 3-12 mm and a diameter of 10-20 μm.

[0013] Furthermore, to ensure that each component performs optimally in its designed function, this scheme clearly specifies its specific type and specifications. The phenolic resin is a thermoplastic phenolic resin, which exhibits specific dissolution and phase change behavior in alkaline environments, making it a key material choice for achieving the dual functions of "in-situ pore formation and interface reinforcement." The glass fiber is alkali-free glass fiber, whose composition improves its durability in strongly alkaline environments. Its length is limited to 3-12 mm, and its diameter to 10-20 μm. This size specification aims to ensure that the fiber effectively performs its bridging, crack-resistant, reinforcing, and toughening functions, while avoiding difficulties in dispersion or the introduction of defects into the matrix due to excessively long or thick fibers, or insufficient reinforcement due to excessively short or thin fibers. This is an important guarantee for optimizing mechanical properties.

[0014] Secondly, the present invention provides a method for preparing a geopolymer thermal insulation solution for lead-zinc tailings, comprising: S1: adding sodium hydroxide to water, stirring until completely dissolved, and cooling to room temperature; then heating to 50°C and maintaining a constant temperature, adding sodium silicate powder in batches, and stirring continuously until completely dissolved to obtain an alkaline activator solution. Furthermore, a measured amount of solid sodium hydroxide is slowly added to deionized water while simultaneously stirring thoroughly with a mechanical stirrer to ensure complete dissolution and the release of a large amount of heat. The resulting strongly alkaline solution is then allowed to cool naturally to room temperature (approximately 25°C) to avoid adverse effects on the subsequent dissolution of sodium silicate. Next, the solution is heated to 50°C and maintained at this constant temperature. At this temperature, solid sodium silicate powder with a modulus of 2.88 is slowly added in batches, with thorough stirring after each addition to prevent localized high concentrations that could lead to clumping or gelation, until all the sodium silicate is completely dissolved, forming a clear, homogeneous, and viscous alkaline activator solution. This provides the necessary alkaline environment and silicon source for the subsequent geopolymerization reaction.

[0015] S2: Cool the alkaline activator solution to room temperature, add lead-zinc tailings and fly ash in sequence, stir evenly, and obtain modified geopolymer slurry; Furthermore, after the alkali activator solution cools to room temperature, lead-zinc tailings and fly ash are added sequentially according to the formulation ratio. Lead-zinc tailings, as the main silica-alumina raw material, not only realizes the resource utilization of solid waste but also provides the active components required for the geopolymer network structure; fly ash further supplements the active silica-alumina components and improves the workability of the slurry. The entire mixing process is carried out at a stirring speed of 500 rpm for 1 to 2 minutes to ensure that the solid particles are uniformly dispersed in the alkali activator, avoiding agglomeration, thereby obtaining a modified geopolymer slurry with good flowability and uniform component distribution. S3: Add phenolic resin, glass fiber and hydrogen peroxide solid powder to the slurry in sequence, and continue to stir and mix to obtain foamed modified slurry; Furthermore, phenolic resin, chopped glass fibers, and hydrogen peroxide solid powder are sequentially introduced into the prepared geopolymer slurry. Phenolic resin, as an organic-inorganic composite modifier, enhances the material's toughness and thermal stability; glass fibers reinforce the skeleton, improving mechanical strength and inhibiting cracking; while hydrogen peroxide acts as a chemical foaming agent, slowly decomposing in an alkaline environment to generate oxygen and form a uniform microporous structure. This mixing process is carried out at high speed (1500 r / min) for 3 to 5 minutes to ensure that the additives are fully dispersed and undergo preliminary physicochemical reactions with the slurry, ultimately obtaining a foamed modified slurry with controllable porosity, good stability, and castability.

[0016] S4: Pour the slurry into a polytetrafluoroethylene mold, cure it under constant temperature conditions, and then cure it at room temperature for 28 days after demolding. Furthermore, the prepared foamed modified slurry was rapidly poured into a pre-prepared polytetrafluoroethylene (PTFE) mold. PTFE possesses excellent demolding properties and chemical inertness, preventing side reactions with the slurry. The mold was then placed in an 80°C constant-temperature oven for 24 hours to promote the initial curing of the geopolymerization reaction (i.e., the "pre-curing" stage), allowing the slurry to gradually lose its fluidity and form a preliminary set with a certain strength. After curing, the mold was removed, and the sample was placed in a standard laboratory environment (room temperature, natural humidity) for another 28 days to allow the geopolymerization reaction to proceed fully and the network structure to further densify, thereby obtaining a precursor material with basic mechanical properties and a porous structure.

[0017] S5: Place the cured sample in a reaction vessel, add 2 mol / L sodium hydroxide solution for hydrothermal treatment, and then wash and dry to obtain the thermal insulation material.

[0018] Furthermore, to optimize the microstructure and thermal insulation performance of the material, the samples, after 28 days of curing, were transferred to a high-pressure reactor and completely immersed in a 2 mol / L sodium hydroxide solution. Hydrothermal treatment was then carried out under high temperature and pressure conditions of 200℃ for 48 hours. The alkaline hydrothermal environment promoted rearrangement of the geopolymer network, crystalline phase transformation, and pore refinement, significantly improving the material's pore uniformity and thermal stability. After the reaction, the samples were removed and repeatedly washed with a large amount of deionized water until the pH of the washing solution was close to neutral to completely remove residual alkali. Finally, the samples were dried in an 80℃ oven to constant weight, yielding a lead-zinc tailings geopolymer thermal insulation material with low thermal conductivity, high porosity, and good durability.

[0019] This invention provides a method for preparing a geopolymer thermal insulation solution for lead-zinc tailings, wherein, in step 1, the alkaline activator solution is prepared by mixing 11-33 parts of solid sodium silicate with a modulus of 2.88, 9-40 parts of sodium hydroxide, and 40-55 parts of water.

[0020] Furthermore, the alkaline activator is prepared by mixing 11–33 parts of solid sodium silicate (Na₂O·2.88SiO₂) with a modulus of 2.88, 9–40 parts of solid sodium hydroxide, and 40–55 parts of deionized water in proportion to their mass. The sodium silicate with a modulus of 2.88 provides a suitable silicon-to-oxygen ratio, which is beneficial for forming a stable three-dimensional aluminosilicate network; while the sodium hydroxide is used to adjust the alkalinity of the system and activate the amorphous silicon-aluminum components in lead-zinc tailings and fly ash. The control of the water volume balances the fluidity of the solution with the alkalinity concentration, ensuring that the activator can both fully wet the solid raw materials and possess sufficient reaction driving force.

[0021] This invention provides a method for preparing a geopolymer thermal insulation material for lead-zinc tailings, wherein the stirring speed in step S2 is 500 r / min and the stirring time is 1-2 min; and the stirring speed in step S3 is 1500 r / min and the stirring time is 3-5 min.

[0022] Furthermore, in step S2, when adding lead-zinc tailings and fly ash to the cooled alkali activator solution, a medium-speed stirring of 500 rpm is used for 1-2 minutes to achieve rapid wetting and initial dispersion of solid particles, avoiding excessive air bubbles or slurry splashing due to excessive stirring, and preventing agglomeration due to insufficient stirring. In step S3, after adding phenolic resin, glass fiber, and hydrogen peroxide foaming agent, the stirring speed needs to be increased to 1500 rpm and the stirring time extended to 3-5 minutes to ensure high dispersion of high-viscosity organic components and chopped fibers in the slurry, while promoting uniform distribution of hydrogen peroxide, providing conditions for subsequent controllable foaming, thereby obtaining a porous geopolymer system with uniform pore size and stable structure.

[0023] This invention provides a method for preparing a geopolymer thermal insulation material for lead-zinc tailings, wherein the curing condition in S4 is a constant temperature of 80°C for 24 hours.

[0024] Furthermore, the cast samples were placed in a constant temperature environment of 80°C for 24 hours. This condition, higher than room temperature, accelerates the kinetics of the polycondensation reaction while avoiding excessively high temperatures that could cause rapid moisture evaporation or early cracking. At 80°C, the aluminosilicate monomers rapidly depolymerize, migrate, and rearrange, forming a preliminary three-dimensional network structure, giving the preform sufficient demolding strength. This heat curing regime effectively promotes early strength development and lays the foundation for continuous densification and structural optimization during the subsequent 28-day room temperature curing period. It is a necessary process step to achieve high material performance and dimensional stability.

[0025] This invention provides a method for preparing a geopolymer thermal insulation material for lead-zinc tailings, wherein: in step S5, the hydrothermal reaction temperature is 200℃ and the reaction time is 48h.

[0026] Furthermore, the cured samples were placed in a high-pressure reactor and reacted with a 2 mol / L sodium hydroxide solution at 200°C and high pressure for 48 hours. Under these conditions, the geopolymer framework underwent alkaline hydrothermal alteration and recrystallization, transforming the amorphous phase into a more ordered zeolite-like microcrystalline phase (such as sodalite and chalcogenide), while simultaneously refining and homogenizing the microporous structure. This structural evolution significantly reduced the material's thermal conductivity and enhanced its long-term durability, making it more suitable for applications such as building insulation.

[0027] This invention provides a method for preparing a geopolymer thermal insulation material for lead-zinc tailings, wherein, in step S5, after hydrothermal treatment, the sample is washed with deionized water until the washing solution is neutral, and then dried at 80°C to constant weight.

[0028] Furthermore, the sample is repeatedly rinsed with deionized water until the pH of the wash solution is close to neutral (usually pH≈7) to thoroughly remove free Na. + and OH - Ions. Subsequently, the washed sample was placed in an 80℃ forced-air drying oven and dried to constant weight, i.e., the difference in mass between two consecutive weighings does not exceed 0.1%. This drying temperature can effectively remove physically adsorbed water and some bound water, while avoiding the pyrolysis of organic modified components (such as phenolic resin) or the collapse of the pore structure caused by high temperature, ultimately obtaining a dry, stable, lightweight finished material with excellent thermal insulation properties.

[0029] The beneficial effects of this invention are as follows: By adding thermoplastic phenolic resin, hydrogen peroxide solid powder, and chopped alkali-free glass fibers to a geopolymer slurry and achieving uniform dispersion under high-speed stirring, not only is the initial micropores formed by the decomposition of hydrogen peroxide in an alkaline environment, but the phenolic resin is also selectively dissolved under subsequent hydrothermal conditions, constructing a continuous and stable multi-level porous structure in situ. Simultaneously, the glass fibers undergo moderate surface etching in a strongly alkaline hydrothermal environment, forming interfacial micropores and playing a bridging and reinforcing role, thus achieving both lightweight thermal insulation and mechanical toughness. Furthermore, by placing the cured preform in a 2 mol / L sodium hydroxide solution at 200°C for a long-term hydrothermal treatment, the amorphous network of the geopolymer undergoes controlled rearrangement and partial zeolization, refining the pore wall structure, improving pore uniformity, and thoroughly removing residual stress and soluble impurities, ultimately obtaining a thermal insulation material with low thermal conductivity, high dimensional stability, and environmental durability. By combining lead-zinc tailings and fly ash as main raw materials, using alkali activators with optimized modulus, precisely controlled liquid-solid ratio and silicon-aluminum ratio, and employing staged gradient stirring and stepped solidification-curing-hydrothermal processes, the entire solution achieves synergistic effects of solid waste resource utilization, precise control of pore structure, and integrated material functions. It is particularly suitable for scenarios with high requirements for lightweight, fireproof, and environmentally friendly thermal insulation materials, such as building energy conservation and industrial insulation. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a process flow diagram for preparing the phenolic resin / glass fiber / alkaline hydrothermal environment modified thermal insulation material of the present invention.

[0032] Figure 2 The image shows the Fourier transform infrared spectrum of the geopolymer sample.

[0033] Figure 3 This is a low-temperature liquid nitrogen adsorption diagram of the geopolymer sample.

[0034] Figure 4 The pore size distribution (2-150 nm) of the mesopores and macropores in the geopolymer samples is shown.

[0035] Figure 5 The micropore size distribution (0-2 nm) of the geopolymer sample is shown.

[0036] Figure 6 The images are field emission electron microscope (FEM) images of geopolymer samples. a) is a conventional solid waste geopolymer made from fly ash raw material; b) is a phenolic resin modified geopolymer; c) shows the macroscopic pore framework of the phenolic resin modified geopolymer; d) is a phenolic resin / alkaline hydrothermal environment modified geopolymer; e) shows the zeolite crystals of the phenolic resin / alkaline hydrothermal environment modified geopolymer; and f) is a phenolic resin / glass fiber / alkaline hydrothermal environment modified geopolymer.

[0037] Figure 7 These are computed tomography (CT) images of geopolymer samples: a) phenolic resin modified geopolymer, b) phenolic resin / alkaline hydrothermal environment modified geopolymer, and c) phenolic resin / glass fiber / alkaline hydrothermal environment modified geopolymer.

[0038] Figure 8 Stress-strain diagram of phenolic resin modified geopolymer.

[0039] Figure 9 Stress-strain diagram of phenolic resin / alkaline hydrothermal environment modified geopolymer.

[0040] Figure 10 Stress-strain diagrams for phenolic resin / glass fiber / alkaline hydrothermal modified geopolymers.

[0041] Figure 11A schematic diagram illustrating the mechanism of increased porosity in polymer thermal insulation materials for solid waste sites under alkaline conditions. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0044] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0045] Reference Figures 1-11 This is one embodiment of the present invention, which provides a lead-zinc tailings base geopolymer thermal insulation material and its preparation method, including the following steps: The implementation method adopted an orthogonal experimental design with 16 groups of experiments of four factors and four levels as examples (A-1 to A-16), as well as comparative examples (A-5HC), comparative example (B-1), and comparative example (B-2).

[0046] The silicon-to-aluminum molar ratio (Si / Al) is one of the core factors controlling the structure and properties of geopolymer gel networks. This study controlled it within the range of 2.2-2.8. Within this range, it is beneficial to form a moderately polymerized and structurally stable three-dimensional aluminosilicate network. This network can provide suitable early slurry structural strength, effectively stabilize bubbles introduced during the foaming process, and promote the formation of uniform and fine micropores. If the Si / Al ratio is too high (>2.8), the cross-linking degree of the system may be insufficient, the gelation process will be delayed, it will not be conducive to the early fixation of bubbles, and it will easily lead to pore coalescence; conversely, if the Si / Al ratio is too low, the network will be too rigid and brittle, which is not conducive to the formation of a porous structure with good elasticity. The alkali activator modulus (Ms) directly affects the alkalinity and silicon species supply of the reaction system. This study set the Ms range to 2-2.6. A suitable modulus can provide sufficient OH- -This study aims to effectively activate fly ash and slag while providing an appropriate amount of soluble silicate ions to participate in the polycondensation reaction, promoting the formation of a uniform and dense gel phase and providing a stable framework for the pore structure. A low modulus results in a vigorous reaction and large shrinkage; a high modulus leads to insufficient reaction driving force. The water-to-solid ratio is a key process parameter determining the workability, final porosity, and density of the slurry. This study sets its range at 0.4-0.55. An appropriate water-to-solid ratio ensures good flowability of the mixture and forms an appropriate amount of gel pores and capillaries after solidification, achieving a lightweight material. If the water-to-solid ratio is too high (>0.55), it easily leads to slurry segregation, coarsening of pores, increased connectivity, and dilution of alkali concentration, which is detrimental to the full development of the gel network.

[0047] Details are as shown in Table 1: Table 1 Experimental group setup

[0048] Since the manufacturing processes are similar, the manufacturing flow of some samples is listed below. It should be noted that the images in the attached figures require the relevant data from the 19 experimental groups in Table 1. Group A-5 geopolymer has the lowest thermal conductivity, and it undergoes hydrothermal conversion to form group A-5HC geopolymer. The control group B-1 geopolymer only added 1g of glass fiber to group A-5, with other additives in the same proportions. The control group B-2 geopolymer was obtained by hydrothermal conversion based on group B-1, with both groups having the same additive proportions. In the above 19 experiments, the total mass of lead-zinc tailings and fly ash was used as the solid waste-based material benchmark, and the addition of hydrogen peroxide powder was controlled at 0.8%; glass fiber was added only 1% to control groups B-1 and B-2, and no glass fiber was added to the other groups. This allows for the exploration of the effects of the silicon-to-aluminum ratio, water-to-solid ratio, alkali activator modulus, and phenolic resin on the thermal insulation performance of the materials.

[0049] Example A-5 group The A-5 group solid waste base geopolymer thermal insulation material, by weight fraction, consists of the following components: 50 parts lead-zinc tailings, 50 parts fly ash, 0.8 parts analytical grade hydrogen peroxide powder, 12 parts phenolic resin, and 74.39 parts alkali activator.

[0050] The alkali activator is prepared by mixing 18.72 parts of sodium silicate (modulus 2.88), 15.67 parts of sodium hydroxide, and 40 parts of water. During material preparation, the water-to-solid ratio is controlled at 0.4, the silicon-to-aluminum molar ratio at 2.4, and the material is cured at a constant temperature of 80 °C.

[0051] After preparing the above materials, the specific production method includes the following steps: S1: Preparation of alkaline activator solution Analytical grade sodium hydroxide granules were slowly added to ultrapure water and magnetically stirred until fully dissolved; then allowed to cool to room temperature. The resulting solution was placed in a 50 °C constant temperature water bath, and sodium silicate powder was added in batches under continuous stirring until completely dissolved, yielding a homogeneous and stable alkali activator solution.

[0052] S2: Preparation of Modified Geopolymer-Based Slurry After the alkaline activator solution obtained from S1 was allowed to stand at room temperature, lead-zinc tailings and fly ash were slowly added. Then, the mixture was stirred at 500 r / min for 1-2 min on a disperser to achieve full wetting and uniform dispersion of the powdered components in the alkaline medium, thus obtaining the modified geopolymer-based slurry.

[0053] S3: Construction of Geological Polymer Slurry for Solid Waste Base In the S2 base slurry, phenolic resin and hydrogen peroxide are introduced sequentially. The disperser speed is increased to 1500 r / min and vigorously stirred for 3-5 min to promote the synergistic mixing of the resin phase and the inorganic slurry and the uniform introduction of the foaming agent, so as to obtain a solid waste base polymer functional slurry with uniform component distribution.

[0054] S4: Molding, Curing, and Room Temperature Maintenance The functional geopolymer slurry prepared by S3 was slowly injected into a polytetrafluoroethylene mold, cured at a constant temperature of 80 ℃ for 24 h, demolded, and then cured at room temperature for 28 days.

[0055] Example A-5HC hydrothermal conversion group The solid waste base polymer thermal insulation material of group A-5HC consists of the following components by weight fraction: 50 parts lead-zinc tailings, 50 parts fly ash, 0.8 parts analytical grade hydrogen peroxide powder, 12 parts phenolic resin, and 74.39 parts alkali activator.

[0056] The alkali activator is prepared by mixing 18.72 parts of sodium silicate (modulus 2.88), 15.67 parts of sodium hydroxide, and 40 parts of water. During material preparation, the water-to-solid ratio is controlled at 0.4, the silicon-to-aluminum molar ratio at 2.4, and the material is cured at a constant temperature of 80 °C.

[0057] After preparing the above materials, the specific production method includes the following steps: S1: Preparation of alkaline activator solution Analytical grade sodium hydroxide granules were slowly added to ultrapure water and magnetically stirred until fully dissolved; then allowed to cool to room temperature. The resulting solution was placed in a 50 °C constant temperature water bath, and sodium silicate powder was added in batches under continuous stirring until completely dissolved, yielding a homogeneous and stable alkali activator solution.

[0058] S2: Preparation of Modified Geopolymer-Based Slurry After the alkaline activator solution obtained from S1 was allowed to stand at room temperature, lead-zinc tailings and fly ash were slowly added. Then, the mixture was stirred at 500 r / min for 1-2 min on a disperser to achieve full wetting and uniform dispersion of the powdered components in the alkaline medium, thus obtaining the modified geopolymer-based slurry.

[0059] S3: Construction of Geological Polymer Slurry for Solid Waste Base In the S2 base slurry, phenolic resin and hydrogen peroxide are introduced sequentially. The disperser speed is increased to 1500 r / min and vigorously stirred for 3-5 min to promote the synergistic mixing of the resin phase and the inorganic slurry and the uniform introduction of the foaming agent, so as to obtain a solid waste base polymer functional slurry with uniform component distribution.

[0060] S4: Molding, Curing, and Room Temperature Maintenance The functional geopolymer slurry prepared by S3 was slowly injected into a polytetrafluoroethylene mold, cured at a constant temperature of 80 ℃ for 24 h, demolded, and then cured at room temperature for 28 days.

[0061] S5: Alkaline hydrothermal treatment and post-treatment drying The S4-demolded block was placed in a high-pressure reactor, and a 2 mol / L sodium hydroxide solution was added as a hydrothermal medium, ensuring that the sample was completely submerged. The hydrothermal reaction was carried out at 200 °C for 48 h. After the reaction, the system was allowed to cool naturally to room temperature. The sample was then removed and repeatedly washed with deionized water until the washing solution was neutral. Finally, the sample was dried in an 80 °C oven to constant weight.

[0062] Comparative Example B-1 Group B-1 solid waste base geopolymer thermal insulation material, by weight fraction, consists of the following components: 50 parts lead-zinc tailings, 50 parts fly ash, 0.8 parts analytical grade hydrogen peroxide powder crystals, 12 parts phenolic resin, 1 part glass fiber, and 74.39 parts alkali activator.

[0063] The alkali activator is prepared by mixing 18.72 parts of sodium silicate (modulus 2.88), 15.67 parts of sodium hydroxide, and 40 parts of water. During material preparation, the water-to-solid ratio is controlled at 0.4, the silicon-to-aluminum molar ratio at 2.4, and the material is cured at a constant temperature of 80 °C.

[0064] After preparing the above materials, the specific production method includes the following steps: S1: Preparation of alkaline activator solution Analytical grade sodium hydroxide granules were slowly added to ultrapure water and magnetically stirred until fully dissolved; then allowed to cool to room temperature. The resulting solution was placed in a 50 °C constant temperature water bath, and sodium silicate powder was added in batches under continuous stirring until completely dissolved, yielding a homogeneous and stable alkali activator solution.

[0065] S2: Preparation of Modified Geopolymer-Based Slurry After the alkaline activator solution obtained from S1 was allowed to stand at room temperature, lead-zinc tailings and fly ash were slowly added. Then, the mixture was stirred at 500 r / min for 1-2 min on a disperser to achieve full wetting and uniform dispersion of the powdered components in the alkaline medium, thus obtaining the modified geopolymer-based slurry.

[0066] S3: Construction of Geological Polymer Slurry for Solid Waste Base In the S2 base slurry, phenolic resin, hydrogen peroxide, and glass fiber are introduced sequentially. The disperser speed is increased to 1500 r / min, and the mixture is vigorously stirred for 3-5 min to promote the synergistic mixing of the resin phase and the inorganic slurry, the uniform introduction of the foaming agent, and the effective dispersion of the fiber, thereby obtaining a solid waste-based geopolymer functional slurry with uniform component distribution.

[0067] S4: Molding, Curing, and Room Temperature Maintenance The functional geopolymer slurry prepared by S3 was slowly injected into a polytetrafluoroethylene mold, cured at a constant temperature of 80 ℃ for 24 h, demolded, and then cured at room temperature for 28 days.

[0068] Comparative Example B-2 The B-2 group solid waste base geopolymer thermal insulation material is composed of the following components by weight fraction: 50 parts lead-zinc tailings, 50 parts fly ash, 0.8 parts analytical grade hydrogen peroxide powder crystals, 12 parts phenolic resin, 1 part glass fiber, and 74.39 parts alkali activator.

[0069] The alkali activator is prepared by mixing 18.72 parts of sodium silicate (modulus 2.88), 15.67 parts of sodium hydroxide, and 40 parts of water. During material preparation, the water-to-solid ratio is controlled at 0.4, the silicon-to-aluminum molar ratio at 2.4, and the material is cured at a constant temperature of 80 °C.

[0070] After preparing the above materials, the specific production method includes the following steps: S1: Preparation of alkaline activator solution Analytical grade sodium hydroxide granules were slowly added to ultrapure water and magnetically stirred until fully dissolved; then allowed to cool to room temperature. The resulting solution was placed in a 50 °C constant temperature water bath, and sodium silicate powder was added in batches under continuous stirring until completely dissolved, yielding a homogeneous and stable alkali activator solution.

[0071] S2: Preparation of Modified Geopolymer-Based Slurry After the alkaline activator solution obtained from S1 was allowed to stand at room temperature, lead-zinc tailings and fly ash were slowly added. Then, the mixture was stirred at 500 r / min for 1-2 min on a disperser to achieve full wetting and uniform dispersion of the powdered components in the alkaline medium, thus obtaining the modified geopolymer-based slurry.

[0072] S3: Construction of Geological Polymer Slurry for Solid Waste Base In the S2 base slurry, phenolic resin, hydrogen peroxide, and glass fiber are introduced sequentially. The disperser speed is increased to 1500 r / min, and the mixture is vigorously stirred for 3-5 min to promote the synergistic mixing of the resin phase and the inorganic slurry, the uniform introduction of the foaming agent, and the effective dispersion of the fiber, thereby obtaining a solid waste-based geopolymer functional slurry with uniform component distribution.

[0073] S4: Molding, Curing, and Room Temperature Maintenance The functional geopolymer slurry prepared by S3 was slowly injected into a polytetrafluoroethylene mold, cured at a constant temperature of 80 ℃ for 24 h, demolded, and then cured at room temperature for 28 days.

[0074] S5: Alkaline hydrothermal treatment and post-treatment drying The demolded block from S4 was placed in a high-pressure reactor, and a 2 mol / L sodium hydroxide solution was added as a hydrothermal medium, ensuring the sample was completely submerged. The hydrothermal reaction was carried out at 200 °C for 48 h. After the reaction, the system was allowed to cool naturally to room temperature. The sample was then removed and repeatedly washed with deionized water until the washings were neutral. Finally, the sample was dried in an 80 °C oven to constant weight, thus obtaining the solid waste-based geopolymer insulation material.

[0075] Performance Analysis The samples were subjected to Fourier transform infrared spectroscopy (FTIR), field emission electron microscopy (SEM), specific surface area and porosity analysis, thermal conductivity analysis, and compressive strength testing.

[0076] 1) Thermal conductivity analysis As shown in Table 2, lead-zinc tailings are rich in high atomic weight heavy metal components such as iron and zinc. During alkali activation, these components participate in the reaction, not only generating C-(A)-SH gel, but also forming iron-containing gel phases (such as (C,F)-ASH) and magnetite (Fe3O4) crystalline phases in situ. These multi-component heavy phases can effectively scatter and impede phonon transmission, significantly improving the intrinsic thermal resistance of the matrix. In addition, the differences in the reactivity of the multiple components in the raw materials can spontaneously induce richer micro-region stresses and interfaces during the curing process, thereby forming a complex and tortuous multi-scale porous network, greatly extending the heat flow path and contributing to a lower thermal conductivity in the material.

[0077] Further comparison of the thermal conductivity of different polymers in Table 3 shows that the thermal insulation performance of the material can be effectively controlled through process and formulation: Group A-5 is a phenolic resin modified sample with a thermal conductivity of 0.1906 W / m·K. Based on this, the thermal conductivity of group A-5HC, after alkaline hydrothermal treatment, decreased to 0.1613 W / m·K, a reduction of approximately 15.4% compared to group A-5. This is because alkaline hydrothermal treatment not only dissolves the phenolic resin embedded in the polymer to form in-situ pores, but also promotes the phase transformation of the polymer into zeolite to form micropores, comprehensively improving the material's porosity and enhancing its thermal insulation performance. Meanwhile, group B-1, modified with added glass fiber, showed a significant increase in thermal conductivity to 0.3385 W / m·K. The core reason is that glass fiber itself has high thermal conductivity (typically 0.04-1.3 W / m·K) and easily forms a continuous thermally conductive network in the matrix, offsetting the thermal insulation effect brought by the porosity. Group B-2, which underwent additional alkaline hydrothermal treatment on top of group B-1, saw a substantial decrease in thermal conductivity to 0.159 W / m·K. The W / m·K ratio was reduced by about 53% compared to group B-1, and even slightly lower than group A-5HC. This again shows that alkaline hydrothermal treatment can greatly increase the porosity of the material, while destroying the continuous thermal conductivity network constructed by glass fibers. Furthermore, by promoting the interfacial micropores on the glass fibers, the material regains its excellent low thermal conductivity properties.

[0078] Therefore, fly ash, with its high silica and aluminum content and low calcium content, is structurally suitable for preparing thermal insulation geopolymers. Through alkaline hydrothermal treatment or formulation design, its porosity can be effectively controlled, resulting in excellent thermal insulation materials with thermal conductivity as low as 0.159 W / (m·K), demonstrating its controllable potential and application value in the field of building energy conservation and insulation.

[0079] Table 2 Chemical composition of fly ash and lead-zinc tailings obtained by X-ray fluorescence spectrometry

[0080] Table 3 Thermal conductivity of fly ash polymers

[0081] 2) Fourier Transform Infrared Spectroscopy (FTIR) Test Figure 2 As shown: The FTIR spectra of each sample are as follows: Figure 2As shown, all four spectral lines are based on an aluminosilicate / silicate network. In the low wavenumber region, ~460 cm⁻¹ represents Si-O-Si (or Si-O) bending vibration, and ~990 cm⁻¹ represents Si-OT (T=Si or Al) asymmetric stretching vibration, which are the "fingerprint peaks" of the geopolymer / silicate gel network. This indicates that each group of samples has formed a three-dimensional structure mainly based on Si-O-Si / Si-O-Al. At the same time, ~3450 cm⁻¹ (OH stretching) and ~1645-1650 cm⁻¹ (HOH bending) are commonly present in the mid-to-high wavenumber region, indicating the presence of adsorbed water / bound water and hydroxyl environment in the system.

[0082] The presence of a distinct 1270 cm⁻¹ (CO) absorption peak in group A-5 corresponds to CO vibrations in the ether / phenolic ether structure of the phenolic resin, indicating that the phenolic resin was successfully introduced and its structural characteristics were retained in the material. Simultaneously, the ~880 cm⁻¹ (Al-O-Si) peak characterizes the formation of Si-O-Al bonds. Therefore, the inorganic aluminosilicate network of the geopolymer coexists with the phenolic resin, exhibiting a strong overall "organic-inorganic composite" characteristic.

[0083] Compared to group A-5, group A-5HC no longer prominently displays characteristic organic peaks such as 1270 cm⁻¹ (CO). This confirms that after treatment in an alkaline hydrothermal environment, the functional groups related to phenolic resin undergo hydrolysis / degradation, or some organic components are leached out, making the spectrum more dominated by the Si-O network. This indicates that the alkaline hydrothermal environment can dissolve the phenolic resin embedded in the geopolymer and promote the formation of in-situ pores. Furthermore, the area of ​​the Si-OT asymmetric stretching vibration peak in group A-5HC is significantly larger than that in group A-5, which also indicates that hydrothermal treatment can promote condensation polymerization reactions in the geopolymer to facilitate the formation of more gel substances and zeolites.

[0084] The Si-OT / Si-O-Si absorption at 460 cm⁻¹, 690 cm⁻¹, and 990 cm⁻¹ in group B-1 is more significant, which is consistent with the characteristics of the enhanced silicon-oxygen structure signal after the introduction of glass fiber, indicating that the glass fiber and the matrix jointly enhance the contribution of the silicon-oxygen network. At the same time, the 1450 cm⁻¹ (OCO) peak indicates the presence of certain carbonization products (carbonates), and the water peaks at 1650 cm⁻¹ and 3450 cm⁻¹ are more obvious, suggesting that the pore water / bound water content or hydration degree is relatively more prominent.

[0085] Group B-2 still maintains the inorganic network characteristics of ~990 cm⁻¹ (Si-OT) and ~695 cm⁻¹ (Si-OT), indicating that the alkaline hydrothermal environment did not destroy the main aluminosilicate / silicate framework under the reinforcement of glass fiber. At the same time, the water peak changed from 1650 to 1645 cm⁻¹ and from 3450 to 3440 cm⁻¹, indicating that the alkaline hydrothermal treatment changed the ionic environment / carbonation state of carbonate and the binding mode of water, which is a response to the adjustment of microstructure and binding state caused by environmental modulation.

[0086] 3) Low-temperature liquid nitrogen adsorption-desorption isotherm analysis, such as... Figure 3 As shown: In the low-pressure region (P / P0 < 1), the adsorption capacity of group A-5 was small and increased slowly, indicating that the micropore content and its contribution to adsorption were limited. However, in the medium-pressure region (0.1-0.8), the adsorption capacity increased steadily, reflecting a process of multilayer adsorption and gradual participation of mesopores. Furthermore, a significant upward tilt occurred in the high-pressure region (P / P0 > 0.9), indicating a certain proportion of contribution from large mesopores / intergranular pores and a considerable total pore volume. In contrast, group A-5HC showed the lowest adsorption capacity across the entire pressure range, especially at the high-pressure end (P / P0 > 0.9), where the upward tilt was significantly weakened. This suggests that the alkaline hydrothermal environment induced gel network rearrangement, leading to pore wall densification and channel contraction, thereby reducing the accessible pore volume and total pore volume. Group B-1 exhibits a moderately high adsorption capacity across the entire pressure range. Its low-pressure and medium-pressure ranges are similar to those of Group A-5, while the high-pressure end also shows a significant upward tilt, indicating that the introduction of glass fibers has created more slit-like intergranular pores. However, the overall pore volume remains moderate. Group B-2, on the other hand, shows the most outstanding performance, with the highest adsorption capacity across the entire pressure range. Furthermore, it exhibits a strong and sharp increase when P / P0 > 0.9, indicating that it has the largest total pore volume and contains a large number of mesopores and even interconnected intergranular pore networks. At the same time, the continuous upward tilt in the medium-pressure range also suggests a higher degree of mesopore participation and more developed pores. Taking group B-2, which has the lowest thermal conductivity, as an example, it can be found that the introduction of phenolic resin followed by alkaline hydrothermal treatment makes the sample exhibit a clear tendency of hierarchical pores. This confirms that the introduction of phenolic resin and glass fiber, along with alkaline hydrothermal treatment, enables the material to acquire in-situ pores generated by the dissolution of phenolic resin, skeletal pores generated by the phase change zeolite of the geopolymer, and interfacial micropores generated by the erosion of glass fiber by alkaline solution. This effectively increases the total pore volume of the material and reduces the overall thermal conductivity, ultimately optimizing the thermal insulation performance.

[0087] 4) Full pore size analysis, such as Figure 4 , Figure 5 As shown: Within the micropore range (0-2 nm), the pore volume of group A-5 remained low overall, with only slight fluctuations in the pore size distribution curve and no obvious sharp peaks, indicating that the micropore structure development of the material was limited under the condition of only introducing phenolic resin. Group A-5HC showed an increased micropore volume compared to group A-5, suggesting that alkaline hydrothermal treatment may have promoted further rearrangement of the gel network and introduced a certain proportion of micropore contribution, thereby improving the pore structure characteristics to some extent. In contrast, group B-2 exhibited two sharp peaks in the 0.6-1.0 nm range, with a peak pore volume of approximately 0.53 cm³. 3 The pore size / g is much higher than that of groups A-5 and A-5HC, indicating that this group of samples formed a large number of highly concentrated microporous structures. This characteristic pore size is consistent with the typical size of zeolite channels, indicating that zeolite structures are more easily induced under alkaline hydrothermal conditions, which in turn promotes the formation of microporous channels. The introduction of glass fiber further amplifies the microporous contribution of this process. It is because the surface of glass fiber partially dissolves in a strongly alkaline hydrothermal environment and reacts with the geopolymer matrix to form a silicon-rich interfacial transition layer, which easily generates interfacial micropores. Therefore, its micropore porosity is significantly increased, which further promotes the improvement of thermal insulation performance.

[0088] Within the mesoporous and macroporous range (>2 nm), group A-5 had the lowest overall pore volume, increasing only slowly with increasing pore size, indicating limited mesoporous / macroporous content and insufficient pore volume contribution. Group A-5HC had a significantly larger pore volume than A-5, showing a stronger growth trend in the tens to hundreds of nanometer range, indicating that alkaline hydrothermal treatment was more conducive to the formation or connectivity improvement of mesopores / macropores, but its overall pore volume was still significantly lower than B-2. Group B-2 had the highest pore volume in the mesoporous-macroporous region, increasing continuously and steeply with increasing pore size, indicating that it not only had well-developed mesopores but also had significant macroporous / intergranular pore volume contributions, forming a higher porosity hierarchical pore network.

[0089] The above results indicate that the phenolic resin cured in the geopolymer matrix is ​​dissolved or removed in the subsequent alkaline hydrothermal environment. The resulting dissolution pores provide a large number of in-situ pores for the geopolymer. The alkaline hydrothermal environment induces the geopolymer to undergo phase transformation to generate the zeolite phase, which simultaneously promotes the development of micropores and mesopores. The introduction of glass fiber works synergistically with the alkaline hydrothermal process to further form interfacial pores at the fiber interface. These three aspects ultimately achieve a significant improvement in the pore structure of the insulation material to optimize its thermal insulation performance.

[0090] Field emission scanning electron microscopy (SEM) such as Figure 6 As shown: Figure 6a indicates that the fly ash raw material mainly consists of spherical glassy microspheres and their broken fragments. The particles are in a dispersed and aggregated state, lacking a continuous cementing phase between particles, and no obvious agglomeration or consolidation characteristics are observed, indicating that the raw material has not yet undergone significant dissolution-polymerization reactions and structural reconstruction. After the introduction of phenolic resin, the microstructure of the system gradually evolved from "particle stacking" to "gel skeleton": phenolic resin modified geopolymer ( Figure 6 A certain number of pores have appeared in b), but the overall distribution is still relatively localized; further magnification observation ( Figure 6 c) It is evident that the gel phase exhibits fibrous / flocculated interweaving and aggregation, forming a continuous three-dimensional porous framework, resulting in a relatively localized degree of pore development and connectivity. After synergistic modification with phenolic resin and alkaline hydrothermal conditions ( Figure 6 d) The cementation and maturation of the gel phase are further enhanced, the number of pores increases and the pore size distribution tends to be uniform, and the pore wall structure is more stable; at the same time, a large number of columnar (rod-shaped) zeolite crystals can be observed to form in this system. Figure 6 e) indicates that an alkaline hydrothermal environment can effectively induce gel phase crystallization, thereby improving porosity. For phenolic resin / glass fiber / alkaline hydrothermal environment modified samples ( Figure 6 f) The fiber-reinforced phase and the geopolymer matrix exhibit good interfacial bonding characteristics. The embedding and encapsulation of fibers in the skeleton helps to play a supporting and bridging role, thereby inhibiting crack initiation and propagation, and enhancing the mechanical stability and structural integrity of the pore network.

[0091] Compression resistance analysis This invention utilizes a fly ash-lead-zinc tailings slag composite system design, combined with phenolic resin modification and fiber reinforcement, and innovatively introduces an alkaline hydrothermal environment treatment process to successfully construct a multi-scale synergistic pressure-bearing system within the material, consisting of a "high-strength gel matrix-fiber-reinforced network-multi-level closed-cell skeleton." System compressive performance tests demonstrate that the material's load-bearing capacity can be significantly optimized through composition design and process control.

[0092] In the compressive strength test, the phenolic resin modified A-5 group exhibited better thermal insulation performance, with a peak strength of 4.31 MPa, indicating that this formulation is conducive to forming a relatively stable gel matrix while also meeting the load-bearing requirements of the porous structure. After alkaline hydrothermal treatment of the A-5 group, the peak strength of the resulting A-5HC group increased from 4.31 MPa to 4.36 MPa, showing a slight enhancement. This indicates that the alkaline hydrothermal treatment contributes more to the compressive strength of the A-5 system by further strengthening the gel phase and locally reinforcing the pore wall structure, confirming the interfacial bonding effect between the incompletely dissolved residual phase of phenolic resin and the geopolymer skeleton, which can form a strong and tough organic-inorganic composite interface. Introducing glass fiber into the A-5 formulation and performing alkaline hydrothermal treatment resulted in the formation of the B-2 group, which showed a significant improvement in compressive strength, with the peak strength increasing to 6.18 MPa, an improvement of approximately 43.4% compared to the A-5 group. This indicates that the dispersion and bridging effect of glass fibers in the matrix can effectively inhibit crack initiation and propagation, improve the deformation coordination ability of the material during the load-bearing process, and thus significantly enhance the strength and toughness of the composite system.

[0093] Table 4 Peak compressive force data

[0094] Computed Tomography Analysis Figure 7 The image shows the CT 3D reconstruction results of the sample's pore structure (blue area represents pores). A comparison from left to right reveals that the phenolic resin-modified geopolymer ( Figure 7 a) The total number of pores is limited, and their spatial distribution is relatively discrete, mainly consisting of locally aggregated pores. Overall connectivity is low, indicating that although a porous framework has been formed, the degree of pore development is still limited. After treatment in an alkaline hydrothermal environment ( Figure 7 (b) Significantly enhanced pore volume distribution: The number of pores increased significantly, the pore size became more hierarchical, and both micropores and mesopores increased simultaneously. Furthermore, the spatial distribution of pores shifted from "local concentration" to "more widespread distribution," indicating that the alkaline hydrothermal process promotes pore generation and expansion through phenolic resin dissolution—geomer phase transformation to zeolite, leading to a more complete development and reconstruction of the pore network. Further, glass fibers were introduced into the alkaline hydrothermal system (…). Figure 7 After c), the pores exhibited higher development density and more uniform space-filling characteristics, and the pore connectivity was further enhanced. This is not only reflected in the increase in the overall number of pores, but can also be attributed to the dissolution and interface reconstruction of the fiber / matrix interface under alkaline hydrothermal conditions, which induces the formation of a large number of interfacial micropores around the fibers. This transforms the pore structure from "matrix pores as the main component" to "matrix pores + interfacial micropores contributing synergistically." Overall, Figure 7 a to Figure 7 b highlights the effect of alkaline hydrothermal treatment on pore proliferation and homogenization, while Figure 7 b to Figure 7c further demonstrates that the introduction of glass fibers can significantly enhance the development and structural complexity of the pore network through interfacial microporization.

[0095] In summary, the novel solid waste-based geopolymer thermal insulation material provided by this invention exhibits significant advantages in thermal insulation performance, structural stability, and comprehensive mechanical properties. Based on a composite ratio of lead-zinc tailings slag and fly ash, this material incorporates phenolic resin and glass fiber, undergoing alkaline hydrothermal treatment. The in-situ pores generated by the dissolution of phenolic resin, the framework pores of the geopolymer phase change zeolite, and the interfacial micropores generated by the erosion of glass fiber by the alkaline solution lay the structural foundation for constructing a rich and stable porous system and achieving low thermal conductivity. Furthermore, the incompletely dissolved residual phase of phenolic resin bonds with the geopolymer framework at the interface, forming a strong and tough organic-inorganic composite interface, which enhances its mechanical properties. The introduction of glass fiber, through bridging, further maintains the material's high mechanical integrity and long-term durability. This material integrates low thermal conductivity, high stability, good mechanical properties, and solid waste resource utilization, making it suitable for applications such as building energy-saving envelopes and industrial equipment insulation, demonstrating promising engineering application prospects and environmental benefits.

[0096] In summary, this invention, by adding thermoplastic phenolic resin, hydrogen peroxide solid powder, and chopped alkali-free glass fibers to a geopolymer slurry and achieving uniform dispersion under high-speed stirring, not only utilizes the decomposition of hydrogen peroxide in an alkaline environment to generate gas and form initial micropores, but also allows the phenolic resin to selectively dissolve under subsequent hydrothermal conditions, constructing an in-situ interconnected and stable multi-level porous structure. Simultaneously, the glass fibers undergo moderate surface etching in a strongly alkaline hydrothermal environment, forming interfacial micropores and providing bridging reinforcement, thus achieving a balance between lightweight thermal insulation and mechanical toughness. Furthermore, by placing the cured preform in a 2 mol / L sodium hydroxide solution at 200°C for a prolonged hydrothermal treatment, controlled rearrangement and partial zeolization of the geopolymer amorphous network are induced, refining the pore wall structure, improving pore uniformity, and thoroughly removing residual stress and soluble impurities, ultimately obtaining a thermal insulation material with low thermal conductivity, high dimensional stability, and environmental durability. By combining lead-zinc tailings and fly ash as main raw materials, using alkali activators with optimized modulus, precisely controlled liquid-solid ratio and silicon-aluminum ratio, and employing staged gradient stirring and stepped solidification-curing-hydrothermal processes, the entire solution achieves synergistic effects of solid waste resource utilization, precise control of pore structure, and integrated material functions. It is particularly suitable for scenarios with high requirements for lightweight, fireproof, and environmentally friendly thermal insulation materials, such as building energy conservation and industrial insulation.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A lead-zinc tailings base geopolymer thermal insulation material, characterized in that: It comprises, by weight, the following components: 50 parts lead-zinc tailings, 50 parts fly ash, 4-16 parts phenolic resin, 0-1 part glass fiber, 0.8-1 part hydrogen peroxide solid powder, and 60-128 parts alkali activator.

2. The lead-zinc tailings base geopolymer thermal insulation material as described in claim 1, characterized in that: The alkaline activator is composed of sodium hydroxide, sodium silicate and water, and has a modulus of 2-2.

6.

3. The lead-zinc tailings base geopolymer thermal insulation material as described in claim 2, characterized in that: The liquid-to-solid mass ratio of the material is 0.4-0.55, and the silicon-to-aluminum molar ratio is 2.2-2.

8.

4. The lead-zinc tailings base geopolymer thermal insulation material as described in claim 3, characterized in that: The phenolic resin is a thermoplastic phenolic resin, and the glass fiber is an alkali-free glass fiber with a length of 3-12 mm and a diameter of 10-20 μm.

5. A method for preparing a lead-zinc tailings base polymer thermal insulation material, based on the lead-zinc tailings base polymer thermal insulation material according to any one of claims 1 to 7, characterized in that: include, S1: Add sodium hydroxide to water and stir until completely dissolved, then cool to room temperature; then heat to 50°C and maintain constant temperature, add sodium silicate powder in batches and stir continuously until completely dissolved to obtain an alkaline activator solution; S2: Cool the alkaline activator solution to room temperature, add lead-zinc tailings and fly ash in sequence, stir evenly, and obtain modified geopolymer slurry; S3: Add phenolic resin, glass fiber and hydrogen peroxide solid powder to the slurry in sequence, and continue to stir and mix to obtain foamed modified slurry; S4: Pour the slurry into a polytetrafluoroethylene mold, cure it under constant temperature conditions, and then cure it at room temperature for 28 days after demolding. S5: Place the cured sample in a reaction vessel, add 2 mol / L sodium hydroxide solution for hydrothermal treatment, and then wash and dry to obtain the thermal insulation material.

6. The method for preparing lead-zinc tailings base geopolymer thermal insulation as described in claim 5, characterized in that: In S1, the alkaline activator solution is prepared by mixing 11-33 parts of solid sodium silicate with a modulus of 2.88, 9-40 parts of sodium hydroxide, and 40-55 parts of water.

7. The method for preparing lead-zinc tailings base geopolymer thermal insulation as described in claim 5, characterized in that: The stirring speed in step S2 is 500 r / min, and the stirring time is 1 to 2 min; the stirring speed in step S3 is 1500 r / min, and the stirring time is 3 to 5 min.

8. The method for preparing lead-zinc tailings base geopolymer thermal insulation as described in claim 5, characterized in that: The curing conditions for S4 are constant temperature at 80℃ for 24 hours.

9. The method for preparing lead-zinc tailings base geopolymer thermal insulation as described in claim 5, characterized in that: In S5, the hydrothermal reaction temperature is 200℃ and the reaction time is 48h.

10. The method for preparing lead-zinc tailings base geopolymer thermal insulation as described in claim 5, characterized in that: In S5, after hydrothermal treatment, the sample is washed with deionized water until the washing solution is neutral, and then dried at 80°C to constant weight.

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